Board-to-board connector

ABSTRACT

A first hold-down includes a hold-down elastic piece supported like a cantilever beam by a reinforcing plate part. The hold-down elastic piece includes an elastic piece body extending from the reinforcing plate part, and a curve contact part formed at an end of the elastic piece body and projecting toward a CPU board beyond a CPU board opposed surface. A housing is formed in such a way that the curve contact part does not come into contact with the housing when the curve contact part no longer projects toward the CPU board beyond the CPU board opposed surface as a result of the curve contact part being elastically displaced toward an input-output board.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority from Japanese patent application No. 2020-79025, filed on Apr. 28, 2020, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

The present disclosure relates to a board-to-board connector.

Patent Literature 1 (Japanese Unexamined Patent Application Publication No. 2006-156023) discloses a receptacle 103 including a receptacle contactor 100, an insulating housing 101 that accommodates the receptacle contactor 100, and a receptacle fixing plate 102 that fixes the insulating housing 101 to a board.

The receptacle fixing plate 102 includes a fixing leg 104 and a receptacle contact part 105. In the receptacle contact part 105, a contact piece 106A and a contact piece 106B are formed by cutting and bending.

SUMMARY

In the case where a hold-down is provided with an elastic piece having a contact part, there is a possibility that the elastic displacement of the contact part is hindered by the housing.

An object of the present disclosure is to provide a technique to achieve a structure in which a contact part of an elastic piece provided in the hold-down is easily elastically displaceable.

According to an aspect of the present invention, there is provided a board-to-board connector to be mounted on a first board and interposed between the first board and a second board to electrically connect a plurality of pads of the first board with a plurality of pads of the second board respectively, including a flat-plate housing, a plurality of contacts held on the housing, and a hold-down made of metal, wherein the housing includes a second board opposed surface to be opposed to the second board and a hold-down accommodation recess is formed on the second board opposed surface, the hold-down includes a soldering part connectable by soldering to a corresponding pad of the first board, a reinforcing plate part accommodated in the hold-down accommodation recess and covering an inner bottom surface of the hold-down accommodation recess, and a hold-down elastic piece supported like a cantilever beam by the reinforcing plate part, the hold-down elastic piece includes an elastic piece body extending from the reinforcing plate part, and a contact part formed at an end of the elastic piece body and projecting toward the second board beyond the second board opposed surface, and the housing is formed in such a way that the contact part does not come into contact with the housing when the contact part no longer projects toward the second board beyond the second board opposed surface as a result of the contact part being elastically displaced toward the first board.

According to the present disclosure, a contact part of a hold-down elastic piece provided in a hold-down is easily elastically displaceable.

The above and other objects, features and advantages of the present disclosure will become more fully understood fro the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view of an information processing device (first embodiment);

FIG. 2 is an exploded perspective view of the information processing device viewed from another angle (first embodiment);

FIG. 3 is a perspective view of a connector (first embodiment);

FIG. 4 is an exploded perspective view of the connector (first embodiment);

FIG. 5 is a perspective view of a housing (first embodiment);

FIG. 6 is a plan view showing the connector where hold-downs are omitted (first embodiment);

FIG. 7 is a plan view of the connector (first embodiment);

FIG. 8 is an enlarged view of a part A in FIG. 7 (first embodiment);

FIG. 9 is an enlarged view of a part B in FIG. 7 (first embodiment);

FIG. 10 is a perspective view of a hold-down elastic piece before deformation where a housing is cut out for the sake of convenience of description (first embodiment);

FIG. 11 is a side view of the hold-down elastic piece before deformation where a housing is cut out for the sake of convenience of description (first embodiment);

FIG. 12 is a side view of the hold-down elastic piece after deformation where a housing is cut out for the sake of convenience of description (first embodiment);

FIG. 13 is a partially cutout perspective view of the housing to which a contact is attached (first embodiment);

FIG. 14 is a partially cutout perspective view of the housing (first embodiment);

FIG. 15 is a partial cross-sectional view of the housing to which the contact is attached (first embodiment);

FIG. 16 is a perspective view of the contact (first embodiment);

FIG. 17 is an exploded perspective view of a connector (second embodiment); and

FIG. 18 is a view showing a simplified version of FIG. 1 of Japanese Unexamined Patent Application Publication No. 2006-156023.

DESCRIPTION OF EMBODIMENTS First Embodiment

A first embodiment is described hereinafter with reference to FIGS. 1 to 16.

FIGS. 1 and 2 are exploded perspective views of an information processing device 200. As shown in FIGS. 1 and 2, the information processing device 200 includes a CPU board 201, a connector 202, an input-output board 203, and a support board 204. The connector 202 is disposed between the CPU board 201 and the input-output board 203.

The CPU board 201 and the input-output board 203 are rigid boards such as a paper phenolic board or a glass epoxy board, for example.

As shown in FIG. 2, the CPU board 201 includes a connector opposed surface 201A to be opposed to the connector 202. A plurality of pad rows 205 are formed on the connector opposed surface 201A. In this embodiment, six pad rows 205 are formed. The plurality of pad rows 205 extend parallel to one another. The plurality of pad rows 205 are lined up in a direction orthogonal to a direction in which one of the pad rows 205 extends. Each of the pad rows 205 includes a plurality of pads 206. On the connector opposed surface 201A, a first shield pad 206A, a second shield pad 206B, a third shield pad 206C, and a fourth shield pad 206D are formed.

The CPU board 201 has a first bolt fastening hole 207, a second bolt fastening hole 208, a first positioning hole 209, and a second positioning hole 210. The first bolt fastening hole 207 and the second bolt fastening hole 208 are formed in such a way that the plurality of pad rows 205 are located between the first bolt fastening hole 207 and the second bolt fastening hole 208 in the longitudinal direction of each pad row 205. The first positioning hole 209 and the second positioning hole 210 are formed to be adjacent to the first bolt fastening hole 207 in the direction orthogonal to the longitudinal direction of each pad row 205. The first positioning hole 209 and the second positioning hole 210 are formed in such a way that the first bolt fastening hole 207 is located between the first positioning hole 209 and the second positioning hole 210 in the direction orthogonal to the longitudinal direction of each pad row 205.

As shown in FIG. 1, the input-output board 203 includes a connector opposed surface 203A to be opposed to the connector 202. A plurality of pad rows 214 are formed on the connector opposed surface 203A. In this embodiment, six pad rows 214 are formed. The plurality of pad rows 214 extend parallel to one another. The plurality of pad rows 214 are lined up in a direction orthogonal to a direction in which one of the pad rows 214 extends. Each of the pad rows 214 includes a plurality of pads 215. Further, a plurality of pads 216 for hold-down are formed on the connector opposed surface 203A.

The input-output board 203 has a first bolt fastening hole 217, a second bolt fastening hole 218, a first penetrating hole 219, and a second penetrating hole 220. The first bolt fastening hole 217 and the second bolt fastening hole 218 are formed in such a way that the plurality of pad rows 214 are located between the first bolt fastening hole 217 and the second bolt fastening hole 218 in the longitudinal direction of each pad row 214. The first penetrating hole 219 and the second penetrating hole 220 are formed to be adjacent to the first bolt fastening hole 217 in the direction orthogonal to the longitudinal direction of each pad row 214. The first penetrating hole 219 and the second penetrating hole 220 are formed in such a way that the first bolt fastening hole 217 is located between the first penetrating hole 219 and the second penetrating hole 220 in the direction orthogonal to the longitudinal direction of each pad row 214.

The support board 204 is typically a part of a casing that accommodates the CPU board 201, the connector 202, and the input-output board 203, and it is made of aluminum or aluminum alloy, for example. The support board 204 includes a flat-plate board main body 230, a first nut 231, a second nut 232, a cylindrical first positioning pin 233, and a cylindrical second positioning pin 234.

The first nut 231 is disposed to correspond to the first bolt fastening hole 217 of the input-output board 203.

The second nut 232 is disposed to correspond to the second bolt fastening hole 218 of the input-output board 203.

The cylindrical first positioning pin 233 is disposed to correspond to the first penetrating hole 219 of the input-output board 203.

The cylindrical second positioning pin 234 is disposed to correspond to the second penetrating hole 220 of the input-output board 203.

The connector 202 is surface-mountable by soldering connection on the connector opposed surface 203A of the input-output board 203. As shown in FIGS. 3 and 4, the connector 202 includes a rectangular flat-plate housing 250 made of insulating resin, a plurality of contact rows 251, a first hold-down 252, a second hold-down 253, a third hold-down 254, and a fourth hold-down 255. The plurality of contact rows 251, the first hold-down 252, the second hold-down 253, the third hold-down 254, and the fourth hold-down 255 are held on the housing 250.

As shown in FIGS. 3 and 4, the plurality of contact rows 251 extend parallel to one another. The plurality of contact rows 251 are lined up in a direction orthogonal to a direction in which one of the contact rows 251 extends. As shown in FIG. 4, the plurality of contact rows 251 include six contact rows 251. The six contact rows 251 include a contact row 251A, a contact row 251B, a contact row 251C, a contact row 251D, a contact row 251E, and a contact row 251F. Each contact row 251 includes a plurality of contacts 300 made of metal. The plurality of contacts 300 that belong to each contact row 251 are disposed at a constant pitch.

Each contact 300 is formed by punching and bending a metal plate formed by plating copper or copper alloy, for example. Likewise, the first hold-down 252, the second hold-down 253, the third hold-down 254, and the fourth hold-down 255 are formed by punching and bending a metal plate such as a stainless steel plate, for example.

The terms “vertical direction”, “pitch direction” and “width direction” are defined by referring to FIG. 1. The vertical direction, the pitch direction and the width direction are directions that are orthogonal to one another.

As shown in FIG. 1, the vertical direction is the thickness direction of the housing 250. The vertical direction includes upward and downward. The upward direction is the direction of viewing the CPU board 201 from the housing 250. The downward direction is the direction of viewing the input-output board 203 from the housing 250. The vertical direction is the direction used by way of illustration only and should not be interpreted as limiting the posture of the connector 202 when it is actually used.

The pitch direction is the longitudinal direction of each contact row 251.

The width direction is the direction orthogonal to the vertical direction and the pitch direction. The plurality of contact rows 251 are disposed to separate from each other in the width direction.

FIG. 5 shows the housing 250. As shown in FIG. 5, the housing 250 includes a CPU board opposed surface 250A that is opposed to the CPU board 201 by facing upward, and an input-output board opposed surface 250B that is opposed to the input-output board 203 by facing downward. The housing 250 has a first positioning hole 260 and a second positioning hole 261. The first positioning hole 260 and the second positioning hole 261 are formed to penetrate the housing 250 in the vertical direction.

Referring back to FIG. 1, the overview of the assembly procedure of the information processing device 200 is described.

First, the connector 202 is surface-mounted on the input-output board 203. To be specific, the plurality of contact rows 251 are soldered to the corresponding pad rows 214, and further the first hold-down 252 and the like are soldered to the corresponding pads 216.

Next, the input-output board 203 on which the connector 202 is mounted is attached to the support board 204. At this time, the first nut 231 penetrates the first bolt fastening hole 217, and the second nut 232 penetrates the second bolt fastening hole 218. Likewise, the first positioning pin 233 penetrates the first penetrating hole 219 and the first positioning hole 260 in this recited order, and the second positioning pin 234 penetrates the second penetrating hole 220 and the second positioning hole 261 in this recited order.

Then, the CPU board 201 is attached to the support board 204 in such a way that the CPU board 201 overlaps the connector 202. At this time, the first positioning pin 233 penetrates the first positioning hole 209, and the second positioning pin 234 penetrates the second positioning hole 210. In this state, a first bolt 211 is fastened to the first nut 231 through the first bolt fastening hole 207, and a second bolt 212 is fastened to the second nut 232 through the second bolt fastening hole 208. In this manner, the connector 202 is interposed between the CPU board 201 and the input-output board 203, and thereby the plurality of pads 215 of the input-output board 203 and the plurality of pads 206 of the CPU board 201 are respectively electrically connected to one another through the plurality of contacts 300. Likewise, the connector 202 is interposed between the CPU board 201 and the input-output board 203, and thereby the plurality of pads 216 of the input-output board 203 and the first shield pad 206A and the like of the CPU board 201 are respectively electrically connected to one another through the first hold-down 252 and the like. By this electrical connection, high electromagnetic shield effect of the connector 202 is achieved.

Further, the first positioning pin 233 is inserted into the first positioning hole 260 of the connector 202 and the first positioning hole 209 of the CPU board 201, and the second positioning pin 234 is inserted into the second positioning hole 261 of the connector 202 and the second positioning hole 210 of the CPU board 201, and thereby highly accurate positioning of the CPU board 201 with respect to the connector 202 is achieved.

The connector 202 is described hereinafter in further detail.

As shown in FIG. 5, the housing 250 is formed in a rectangular flat-plate shape. Specifically, the housing 250 includes a first pitch side surface 262, a second pitch side surface 263, a first width side surface 264, and a second width side surface 265. The first pitch side surface 262 and the second pitch side surface 263 are side surfaces orthogonal to the pitch direction. The first pitch side surface 262 and the second pitch side surface 263 are surfaces opposed to each other. The first width side surface 264 and the second width side surface 265 are side surfaces orthogonal to the width direction. The first width side surface 264 and the second width side surface 265 are surfaces opposed to each other.

The housing 250 further includes a first corner part 266, a second corner part 267, a third corner part 268, and a fourth corner part 269. The first corner part 266 is a corner at which the first pitch side surface 262 and the first width side surface 264 intersect. The second corner part 267 is a corner at which the first pitch side surface 262 and the second width side surface 265 intersect. The third corner part 268 is a corner at which the second pitch side surface 263 and the first width side surface 264 intersect. The fourth corner part 269 is a corner at which the second pitch side surface 263 and the second width side surface 265 intersect. Thus, the first corner part 266 and the fourth corner part 269 are located at diagonal positions of the rectangular housing 250 when viewed from above. Likewise, the second corner part 267 and the third corner part 268 are located at diagonal positions of the rectangular housing 250 when viewed from above. The above-described first positioning hole 260 is formed at the first corner part 266. The second positioning hole 261 is formed at the second corner part 267. The housing 250 has only two positioning holes.

On the first pitch side surface 262, a first hold-down press-fit groove 270, a first nut notch 271, and a second hold-down press-fit groove 272 are formed in this recited order from the first width side surface 264 to the second width side surface 265.

On the second pitch side surface 263, a third hold-down press-fit groove 273, a second nut notch 274, a fourth hold-down press-fit groove 275 are formed in this recited order from the first width side surface 264 to the second width side surface 265.

On the CPU board opposed surface 250A, a first hold-down accommodation recess 280, a second hold-down accommodation recess 281, a third hold-down accommodation recess 282, and a fourth hold-down accommodation recess 283 are formed.

On the housing 250, a plurality of contact accommodation parts 284 are further formed.

The first hold-down press-fit groove 270 is a groove for holding the first hold-down 252 by press-fitting.

The second hold-down press-fit groove 272 is a groove for holding the second hold-down 253 by press-fitting.

The third hold-down press-fit groove 273 is a groove for holding the third hold-down 254 by press-fitting.

The fourth hold-down press-fit groove 275 is a groove for holding the fourth hold-down 255 by press-fitting.

The first nut notch 271 is a notch for avoiding the physical interference between the first nut 231 and the housing 250. In order to avoid the physical interference between the first nut 231 and the housing 250 shown in FIG. 1, the housing 250 may be provided with a hole that allows the first nut 231 to penetrate, instead of the first nut notch 271.

The second nut notch 274 is a notch for avoiding the physical interference between the second nut 232 and the housing 250 shown in FIG. 1. In order to avoid the physical interference between the second nut 232 and the housing 250 shown in FIG. 1, it is feasible to form a hole for the second nut 232 to penetrate on the housing 250 rather than forming the second nut notch 274 on the housing 250.

Referring back to FIG. 5, the first hold-down accommodation recess 280 is formed to accommodate the first hold-down 252 so that the first hold-down 252 attached to the housing 250 does not come closer to the CPU board 201 beyond the CPU board opposed surface 250A. The first hold-down accommodation recess 280 is formed at the first corner part 266. The first hold-down accommodation recess 280 is formed to surround the first positioning hole 260 when viewed from above. The depth of the first hold-down accommodation recess 280 is greater than the thickness of the first hold-down 252. An inner bottom surface 280A of the first hold-down accommodation recess 280 has a contact part recess 280B. The contact part recess 280B is formed apart from the first positioning hole 260. The contact part recess 280B is located on a side of the first positioning hole 260 opposite to the side thereof on which the first pitch side surface 262 is located in the pitch direction. The contact part recess 280B is formed by further recessing the inner bottom surface 280A of the first hold-down accommodation recess 280. The contact part recess 280B extends in the width direction. The contact part recess 280B includes an inner bottom surface 280C. The inner bottom surface 280A of the first hold-down accommodation recess 280 and the inner bottom surface 280C of the contact part recess 280B are parallel to each other, and they are surfaces orthogonal to the vertical direction. The inner bottom surface 280A of the first hold-down accommodation recess 280 and the inner bottom surface 280C of the contact part recess 280B are parts of the CPU board opposed surface 250A of the housing 250.

The second hold-down accommodation recess 281 is formed to accommodate the second hold-down 253 so that the second hold-down 253 attached to the housing 250 does not come closer to the CPU board 201 beyond the CPU board opposed surface 250A. The second hold-down accommodation recess 281 is formed at the second corner part 267. The second hold-down accommodation recess 281 is formed to surround the second positioning hole 261 when viewed from above. The depth of the second hold-down accommodation recess 281 is greater than the thickness of the second hold-down 253. An inner bottom surface 281A of the second hold-down accommodation recess 281 has a contact part recess 281B. The contact part recess 281B is formed apart from the second positioning hole 261. The contact part recess 281B is located on a side of the second positioning hole 261 opposite to the side thereof on which the first pitch side surface 262 is located in the pitch direction. The contact part recess 281B is formed by further recessing the inner bottom surface 281A of the second hold-down accommodation recess 281. The contact part recess 281B extends in the width direction. The contact part recess 281B includes an inner bottom surface 281C. The inner bottom surface 281A of the second hold-down accommodation recess 281 and the inner bottom surface 281C of the contact part recess 281B are parallel to each other, and they are surfaces orthogonal to the vertical direction. The inner bottom surface 281A of the second hold-down accommodation recess 281 and the inner bottom surface 281C of the contact part recess 281B are parts of the CPU board opposed surface 250A of the housing 250.

The third hold-down accommodation recess 282 is formed to accommodate the third hold-down 254 so that the third hold-down 254 attached to the housing 250 does not come closer to the CPU board 201 beyond the CPU board opposed surface 250A. The third hold-down accommodation recess 282 is formed at the third corner part 268. The depth of the third hold-down accommodation recess 282 is greater than the thickness of the third hold-down 254. An inner bottom surface 282A of the third hold-down accommodation recess 282 has a contact part recess 282B. The contact part recess 282B is formed by further recessing the inner bottom surface 282A of the third hold-down accommodation recess 282. The contact part recess 282B extends in the width direction. The contact part recess 282B includes an inner bottom surface 282C. The inner bottom surface 282A of the third hold-down accommodation recess 282 and the inner bottom surface 282C of the contact part recess 282B are parallel to each other, and they are surfaces orthogonal to the vertical direction. The inner bottom surface 282A of the third hold-down accommodation recess 282 and the inner bottom surface 282C of the contact part recess 282B are parts of the CPU board opposed surface 250A of the housing 250.

The fourth hold-down accommodation recess 283 is formed to accommodate the fourth hold-down 255 so that the fourth hold-down 255 attached to the housing 250 does not come closer to the CPU board 201 beyond the CPU board opposed surface 250A. The fourth hold-down accommodation recess 283 is formed at the fourth corner part 269. The depth of the fourth hold-down accommodation recess 283 is greater than the thickness of the fourth hold-down 255. An inner bottom surface 283A of the fourth hold-down accommodation recess 283 has a contact part recess 283B. The contact part recess 283B is formed by further recessing the inner bottom surface 283A of the fourth hold-down accommodation recess 283. The contact part recess 283B extends in the width direction. The contact part recess 283B includes an inner bottom surface 283C. The inner bottom surface 283A of the fourth hold-down accommodation recess 283 and the inner bottom surface 283C of the contact part recess 283B are parallel to each other, and they are surfaces orthogonal to the vertical direction. The inner bottom surface 283A of the fourth hold-down accommodation recess 283 and the inner bottom surface 283C of the contact part recess 283B are parts of the CPU board opposed surface 250A of the housing 250.

Each of the contact accommodation parts 284 is a part that accommodates each of the contacts 300. Each of the contact accommodation parts 284 is formed to penetrate the housing 250 in the vertical direction.

FIG. 6 shows the connector 202 viewed from above. Note that, however, the first hold-down 252, the second hold-down 253, the third hold-down 254, and the fourth hold-down 255 are not shown for the sake of convenience of description.

As shown in FIG. 6, the first hold-down press-fit groove 270 and the like are formed on the first pitch side surface 262. Thus, the first pitch side surface 262 exists in a discontinuous manner in the width direction. For the following description, a part of the first pitch side surface 262 which is missing due to the formation of the first hold-down press-fit groove 270 or the like is indicated by a chain double-dashed line, and the first pitch side surface 262 is specified by drawing a leader line of the first pitch side surface 262 from this chain double-dashed line.

Likewise, the third hold-down press-fit groove 273 and the like are formed on the second pitch side surface 263. Thus, the second pitch side surface 263 exists in a discontinuous manner in the width direction. For the following description, a part of the second pitch side surface 263 which is missing due to the formation of the third hold-down press-fit groove 273 or the like is indicated by a chain double-dashed line, and the second pitch side surface 263 is specified by drawing a leader line of the second pitch side surface 263 from this chain double-dashed line.

As shown in FIG. 6, the plurality of contact rows 251 are disposed to be symmetric with respect to a halving line 250C that divides the housing 250 into two halves in the width direction. Among the plurality of contact rows 251, particular attention is focused on a contact row 251A, a contact row 251D, and a contact row 251F.

The contact row 251A, the contact row 251D, and the contact row 251F extend from the first pitch side surface 262 to the second pitch side surface 263.

The first positioning hole 260 is adjacent to the contact row 251A in the pitch direction. The first positioning hole 260 is disposed between the first pitch side surface 262 indicated by the chain double-dashed line and the contact row 251A.

Likewise, the second positioning hole 261 is adjacent to the contact row 251F in the pitch direction. The second positioning hole 261 is disposed between the first pitch side surface 262 indicated by the chain double-dashed line and the contact row 251F.

The distance between the contact row 251A and the first pitch side surface 262 in the pitch direction is defined as a distance D1. Specifically, the distance D1 is the distance between the contact 300 that is closest to the first pitch side surface 262 among the plurality of contacts 300 forming the contact row 251A and the first pitch side surface 262.

Likewise, the distance between the contact row 251F and the first pitch side surface 262 in the pitch direction is defined as a distance D2. Specifically, the distance D2 is the distance between the contact 300 that is closest to the first pitch side surface 262 among the plurality of contacts 300 forming the contact row 251F and the first pitch side surface 262.

Likewise, the distance between the contact row 251D and the first pitch side surface 262 in the pitch direction is defined as a distance D3. Specifically, the distance D3 is the distance between the contact 300 that is closest to the first pitch side surface 262 among the plurality of contacts 300 forming the contact row 251D and the first pitch side surface 262.

In this embodiment, the relationship of D1=D2 is established. Further, in this embodiment, the relationships of D3<D1 and D3<D2 are established. In simpler terms, the contact row 251D is closer to the first pitch side surface 262 than the contact row 251A is, and is also closer to the first pitch side surface 262 than the contact row 251F is.

The first nut notch 271 is open to the first pitch side surface 262 indicated by the chain double-dashed line, and formed between the first pitch side surface 262 indicated by the chain double-dashed line and the contact row 251D.

The distance between the contact row 251A and the second pitch side surface 263 in the pitch direction is defined as a distance E1. Specifically, the distance E1 is the distance between the contact 300 that is closest to the second pitch side surface 263 among the plurality of contacts 300 forming the contact row 251A and the second pitch side surface 263.

Likewise, the distance between the contact row 251F and the second pitch side surface 263 in the pitch direction is defined as a distance E2. Specifically, the distance E2 is the distance between the contact 300 that is closest to the second pitch side surface 263 among the plurality of contacts 300 forming the contact row 251F and the second pitch side surface 263.

Likewise, the distance between the contact row 251D and the second pitch side surface 263 in the pitch direction is defined as a distance E3. Specifically, the distance E3 is the distance between the contact 300 that is closest to the second pitch side surface 263 among the plurality of contacts 300 forming the contact row 251D and the second pitch side surface 263.

In this embodiment, the relationship of E1=E2 is established. Further, in this embodiment, the relationships of E3>E1 and E3>E2 are established. In simpler terms, the contact row 251D is farther from the second pitch side surface 263 than the contact row 251A is, and is also farther from the second pitch side surface 263 than the contact row 251F is.

The second nut notch 274 is open to the second pitch side surface 263 indicated by the chain double-dashed line, and formed between the second pitch side surface 263 indicated by the chain double-dashed line and the contact row 251D.

The first positioning hole 260, the second positioning hole 261, the first hold-down 252, the second hold-down 253, the third hold-down 254, and the fourth hold-down 255 are hereinafter described in further detail with reference to FIGS. 7 to 12. FIG. 8 is an enlarged view of the part A in FIG. 7. FIG. 9 is an enlarged view of the part B in FIG. 7.

As shown in FIG. 8, the first positioning hole 260 is a round hole that penetrates the housing 250 in the vertical direction, and it has an inner edge 260A.

The first hold-down 252 includes a reinforcing plate part 252A, two soldering parts 252B, and a hold-down elastic piece 252P.

The reinforcing plate part 252A is disposed to cover the CPU board opposed surface 250A around the first positioning hole 260. The reinforcing plate part 252A is accommodated in the first hold-down accommodation recess 280 that is formed on the CPU board opposed surface 250A. The reinforcing plate part 252A is disposed in the internal space of the first hold-down accommodation recess 280. The reinforcing plate part 252A is disposed to cover the inner bottom surface 280A of the first hold-down accommodation recess 280. The inner bottom surface 280A of the first hold-down accommodation recess 280 is a part of the CPU board opposed surface 250A. In this structure, the reinforcing plate part 252A is farther from the CPU board 201 than a part 250D of the CPU board opposed surface 250A in which the first hold-down accommodation recess 280 is not formed, while covering the CPU board opposed surface 250A. Therefore, the elastic deformation of each contact 300 is not hindered when pressing the CPU board 201 against the connector 202.

Each of the soldering parts 252B projects from the reinforcing plate part 252A toward the input-output board 203 and is connectable by soldering to the corresponding pad 216 of the input-output board 203. One of the two soldering parts 252B is press-fit into the first hold-down press-fit groove 270 formed on the first pitch side surface 262, and thereby the first hold-down 252 is held by the housing 250. Each of the soldering parts 252B projects downward beyond the input-output board opposed surface 250B of the housing 250 shown in FIG. 5.

Referring back to FIG. 8, the reinforcing plate part 252A has a penetrating hole 252C. The penetrating hole 252C is a round hole that penetrates the reinforcing plate part 252A in the vertical direction, and it has an inner edge 252D.

The penetrating hole 252C is larger than the first positioning hole 260. To be specific, an inside diameter 252E of the penetrating hole 252C is greater than an inside diameter 260B of the first positioning hole 260.

The first hold-down 252 is disposed in such a way that the reinforcing plate part 252A does not cover the inner edge 260A of the first positioning hole 260 when viewed from above. Specifically, the first hold-down 252 is disposed in such a way that the inner edge 260A of the first positioning hole 260 is located radially inward with respect to the inner edge 252D of the penetrating hole 252C when viewed from above.

The reinforcing plate part 252A made of metal thereby does not hinder the positioning function of the inner edge 260A of the first positioning hole 260 and the first positioning pin 233. Further, the reinforcing plate part 252A made of metal reduces the degree of deformation when the first positioning hole 260 is deformed outward in the radial direction due to contact with the first positioning pin 233, which avoids a significant decrease in positioning accuracy of the positioning function.

The hold-down elastic piece 252P is supported like a cantilever beam by the reinforcing plate part 252A. The hold-down elastic piece 252P is disposed opposite to the inner bottom surface 280C of the contact part recess 280B in the vertical direction.

As shown in FIG. 10, the hold-down elastic piece 252P is formed to be elongated in the width direction. The hold-down elastic piece 252P includes an elastic piece body 252Q extending from the reinforcing plate part 252A and a curve contact part 252R formed at the end of the elastic piece body 252Q. The hold-down elastic piece 252P and the elastic piece body 252Q are opposed to the inner bottom surface 280C of the contact part recess 280B with a gap therebetween in the vertical direction.

The elastic piece body 252Q extends in parallel to the CPU board opposed surface 250A.

The curve contact part 252R is formed in a curve that is convex toward the CPU board 201, i.e., upward, and thereby high connection reliability is achieved. As shown in FIG. 11, when no load is imposed on the hold-down elastic piece 252P, the curve contact part 252R partly projects toward the CPU board 201, i.e., upward, beyond the CPU board opposed surface 250A. To be more specific, when no load is imposed on the hold-down elastic piece 252P, a convex curve surface 252S, which corresponds to the upper surface of the curve contact part 252R, projects toward the CPU board 201, i.e., upward, beyond the CPU board opposed surface 250A. The height of projection of the curve contact part 252R from the CPU board opposed surface 250A is referred to as a projecting height 252X. Likewise, when no load is imposed on the hold-down elastic piece 252P, there is a gap between the hold-down elastic piece 252P and the inner bottom surface 280C of the contact part recess 280B.

FIG. 12 shows the state where the CPU board 201 is pressed against the connector 202. In FIG. 12, the thickness of the first shield pad 206A is exaggerated for the sake of convenience of description. As shown in FIG. 12, when the CPU board 201 is pressed against the connector 202, the first shield pad 206A that is disposed on the connector opposed surface 201A of the CPU board 201 butts against the part 250D of the CPU board opposed surface 250A of the housing 250. At this time, the convex curve surface 252S of the curve contact part 252R comes into contact with the first shield pad 206A, and thereby the hold-down elastic piece 252P is elastically deformed downward. In other words, the curve contact part 252R is elastically displaced downward. As a result, the curve contact part 252R no longer projects toward the CPU board 201 beyond the CPU board opposed surface 250A. To be specific, the CPU board opposed surface 250A and an apex 252T of the convex curve surface 252S in the vertical direction are at the same height in the vertical direction.

The housing 250 is formed in such a way that the curve contact part 252R is not in contact with the housing 250 in the state shown in FIG. 12. Specifically, the inner bottom surface 280A of the first hold-down accommodation recess 280 has the contact part recess 280B that is opposed to the curve contact part 252R in the vertical direction. The contact part recess 280B has a sufficient depth so that the curve contact part 252R does not come into contact with the inner bottom surface 280C of the contact part recess 280B when the curve contact part 252R becomes the state shown in FIG. 12. Thus, when pressing the CPU board 201 against the connector 202, the curve contact part 252R does not physically interfere with the inner bottom surface 280A of the first hold-down accommodation recess 280 of the housing 250, thereby achieving flexible elastic displacement of the curve contact part 252R in the vertical direction.

Referring back to FIG. 9, the second positioning hole 261 is a slotted hole that penetrates the housing 250 in the vertical direction. The second positioning hole 261 extends to come closer to the first positioning hole 260. The second positioning hole 261 is elongated in the width direction. The second positioning hole 261 has an inner edge 261A.

The second hold-down 253 includes a reinforcing plate part 253A, two soldering parts 253B, and a hold-down elastic piece 253P.

The reinforcing plate part 253A is disposed to cover the CPU board opposed surface 250A around the second positioning hole 261. The reinforcing plate part 253A is accommodated in the second hold-down accommodation recess 281 that is formed on the CPU board opposed surface 250A. The reinforcing plate part 253A is disposed in the internal space of the second hold-down accommodation recess 281. The reinforcing plate part 253A is disposed to cover the inner bottom surface 281A of the second hold-down accommodation recess 281. The inner bottom surface 281A of the second hold-down accommodation recess 281 is a part of the CPU board opposed surface 250A. In this structure, the reinforcing plate part 253A is farther from the CPU board 201 than the part 250D of the CPU board opposed surface 250A in which the second hold-down accommodation recess 281 is not formed, while covering the CPU board opposed surface 250A. Therefore, the elastic deformation of each contact 300 is not hindered when pressing the CPU board 201 against the connector 202.

Each of the soldering parts 253B projects from the reinforcing plate part 253A toward the input-output board 203 and is connectable by soldering to the corresponding pad 216 of the input-output board 203. One of the two soldering parts 253B is press-fit into the second hold-down press-fit groove 272 formed on the first pitch side surface 262, and thereby the second hold-down 253 is held by the housing 250. Each of the soldering parts 253B projects downward beyond the input-output board opposed surface 250B of the housing 250 shown in FIG. 5.

Referring back to FIG. 9, the reinforcing plate part 253A has a penetrating hole 253C. The penetrating hole 253C is a slotted hole that penetrates the reinforcing plate part 253A in the vertical direction, and it has an inner edge 253D.

The penetrating hole 253C is larger than the second positioning hole 261. To be specific, the inner edge 253D of the penetrating hole 253C has two straight edge parts 253E that are opposed to each other in the pitch direction. The inner edge 261A of the second positioning hole 261 has two straight edge parts 261B that are opposed to each other in the pitch direction. A distance 253F between the two straight edge parts 253E is longer than a distance 261C between the two straight edge parts 261B.

The second hold-down 253 is disposed in such a way that the reinforcing plate part 253A does not cover the inner edge 261A of the second positioning hole 261 when viewed from above. Specifically, the second hold-down 253 is disposed in such a way that the inner edge 261A of the second positioning hole 261 is located inward with respect to the inner edge 253D of the penetrating hole 253C when viewed from above. To be specific, the second hold-down 253 is disposed in such a way that the two straight edge parts 261B are located between the two straight edge parts 253E when viewed from above.

The reinforcing plate part 253A made of metal thereby does not hinder the positioning function of the inner edge 261A of the second positioning hole 261 and the second positioning pin 234. Further, the reinforcing plate part 253A made of metal reduces the degree of deformation when the second positioning hole 261 is deformed outward due to contact with the second positioning pin 234, which avoids a significant decrease in positioning accuracy of the positioning function.

Description about the structure of the hold-down elastic piece 253P and the technical relationship between the hold-down elastic piece 253P and the inner bottom surface 281C of the contact part recess 281B is omitted because it overlaps the description related to the hold-down elastic piece 252P described above.

As shown in FIG. 4, in this embodiment, while the housing 250 is formed integrally, the first hold-down 252 and the second hold-down 253 are separate parts. Thus, referring to FIGS. 7 to 9, the relative positional relationship between the first positioning hole 260 and the second positioning hole 261 in the housing 250 is more easily manageable compared with the relative positional relationship between the penetrating hole 252C of the first hold-down 252 and the penetrating hole 253C of the second hold-down 253. Therefore, since the reinforcing plate part 252A of the first hold-down 252 does not cover the inner edge 260A of the first positioning hole 260 when viewed from above as shown in FIG. 8 and the reinforcing plate part 253A of the second hold-down 253 does not cover the inner edge 261A of the second positioning hole 261 when viewed from above as shown in FIG. 9, the positioning function by the first positioning hole 260 and the second positioning hole 261 is reliably exerted, which achieves high positioning accuracy of the CPU board 201 with respect to the connector 202.

Referring back to FIG. 7, the third hold-down 254 includes a reinforcing plate part 254A, two soldering parts 254B, and a hold-down elastic piece 254P.

The reinforcing plate part 254A is disposed to cover the CPU board opposed surface 250A. The reinforcing plate part 254A is accommodated in the third hold-down accommodation recess 282 that is formed on the CPU board opposed surface 250A. The reinforcing plate part 254A is disposed in the internal space of the third hold-down accommodation recess 282. The reinforcing plate part 254A is disposed to cover the inner bottom surface 282A of the third hold-down accommodation recess 282. The inner bottom surface 282A of the third hold-down accommodation recess 282 is a part of the CPU board opposed surface 250A. In this structure, the reinforcing plate part 254A is farther from the CPU board 201 than the part 250D of the CPU board opposed surface 250A in which the third hold-down accommodation recess 282 is not formed, while covering the CPU board opposed surface 250A. Therefore, the elastic deformation of each contact 300 is not hindered when pressing the CPU board 201 against the connector 202.

Each of the soldering parts 254B projects from the reinforcing plate part 254A toward the input-output board 203 and is connectable by soldering to the corresponding pad 216 of the input-output board 203. One of the two soldering parts 254B is press-fit into the third hold-down press-fit groove 273 formed on the second pitch side surface 263, and thereby the third hold-down 254 is held by the housing 250. Each of the soldering parts 254B projects downward beyond the input-output board opposed surface 250B of the housing 250 shown in FIG. 5.

Description about the structure of the hold-down elastic piece 254P and the technical relationship between the hold-down elastic piece 254P and the inner bottom surface 282C of the contact part recess 282B shown in FIG. 5 is omitted because it overlaps the description related to the hold-down elastic piece 252P described above.

Referring back to FIG. 7, the fourth hold-down 255 includes a reinforcing plate part 255A, two soldering parts 255B, and a hold-down elastic piece 255P.

The reinforcing plate part 255A is disposed to cover the CPU board opposed surface 250A. The reinforcing plate part 255A is accommodated in the fourth hold-down accommodation recess 283 that is formed on the CPU board opposed surface 250A. The reinforcing plate part 255A is disposed in the internal space of the fourth hold-down accommodation recess 283. The reinforcing plate part 255A is disposed to cover the inner bottom surface 283A of the fourth hold-down accommodation recess 283. The inner bottom surface 283A of the fourth hold-down accommodation recess 283 is a part of the CPU board opposed surface 250A. In this structure, the reinforcing plate part 255A is farther from the CPU board 201 than the part 250D of the CPU board opposed surface 250A in which the fourth hold-down accommodation recess 283 is not formed, while covering the CPU board opposed surface 250A. Therefore, the elastic deformation of each contact 300 is not hindered when pressing the CPU board 201 against the connector 202.

Each of the soldering parts 255B projects from the reinforcing plate part 255A toward the input-output board 203 and is connectable by soldering to the corresponding pad 216 of the input-output board 203. One of the two soldering parts 255B is press-fit into the fourth hold-down press-fit groove 275 formed on the second pitch side surface 263, and thereby the fourth hold-down 255 is held by the housing 250. Each of the soldering parts 255B projects downward beyond the input-output board opposed surface 250B of the housing 250 shown in FIG. 5.

Description about the structure of the hold-down elastic piece 255P and the technical relationship between the hold-down elastic piece 255P and the inner bottom surface 283C of the contact part recess 283B shown in FIG. 5 is omitted because it overlaps the description related to the hold-down elastic piece 253P described above.

Each of the contacts 300 and each of the contact accommodation parts 284 are described hereinafter in detail with reference to FIGS. 13 to 16.

As shown in FIGS. 13 and 14, each contact accommodation part 284 is formed to attach each contact 300 to the housing 250. As shown in FIG. 14, each contact accommodation part 284 is formed as a penetrating hole that penetrates the housing 250 in the vertical direction, and it is open to the CPU board opposed surface 250A and the input-output board opposed surface 250B. Each contact accommodation part 284 is composed of a press-fitting space 301, a solder connection checking hole 302, and a separating wall 303. The press-fitting space 301 and the solder connection checking hole 302 are formed apart from each other in the width direction. The separating wall 303 is a wall that separates the press-fitting space 301 from the solder connection checking hole 302 in the width direction.

The press-fitting space 301 is formed as a penetrating hole that penetrates the housing 250 in the vertical direction. Specifically, the press-fitting space 301 is open to the CPU board opposed surface 250A and the input-output board opposed surface 250B. The housing 250 includes, for each press-fitting space 301, two pitch partition surfaces 304 that partitions the press-fitting space 301 in the pitch direction. FIG. 14 shows only one of the two pitch partition surfaces 304. In FIG. 15, the cross-sectional shapes of the press-fitting space 301 and the solder connection checking hole 302 are specified by chain double-dashed lines. As shown in FIG. 15, a press-fit groove 305 that extends in the vertical direction is formed on each pitch partition surface 304. Each pitch partition surface 304 includes a press-fit surface 305A that partitions the press-fit groove 305 in the pitch direction.

Referring back to FIG. 14, the solder connection checking hole 302 is a penetrating hole that penetrates the housing 250 in the vertical direction. Specifically, the solder connection checking hole 302 is open to the CPU board opposed surface 250A and the input-output board opposed surface 250B.

The separating wall 303 is a wall that spatially separates the press-fitting space 301 from the solder connection checking hole 302 as described above, and it is formed between the press-fitting space 301 and the solder connection checking hole 302. As shown in FIG. 15, the separating wall 303 includes a first separating surface 306 that partitions the press-fitting space 301 in the width direction, and a second separating surface 307 that partitions the solder connection checking hole 302 in the width direction. The first separating surface 306 and the second separating surface 307 are surfaces orthogonal to the width direction. As shown in FIGS. 14 and 15, the separating wall 303 has a notch 308 that is open toward the press-fitting space 301 and the solder connection checking hole 302 and is also open to the input-output board opposed surface 250B. The notch 308 is formed at the lower end of the separating wall 303.

FIG. 16 is a perspective view of each contact 300. As shown in FIG. 16, each contact 300 includes a press-fit part 320, a soldering part 321, and an electrical contact spring piece 322.

The press-fit part 320 is a part to be press-fit into the press-fitting space 301 shown in FIG. 15. Specifically, the press-fit part 320 is press-fit into the press-fitting space 301, and thereby each contact 300 is held by the housing 250. Referring back to FIG. 16, the press-fit part 320 is a plate body that is orthogonal to the width direction, and it includes a press-fit part main body 323 and two press-fit claws 324. The two press-fit claws 324 are formed to project in the pitch direction from the both ends of the press-fit part main body 323 in the pitch direction.

The soldering part 321 is a part that is connectable by soldering to the corresponding pad 215 of the input-output board 203 shown in FIG. 1. As shown in FIG. 16, the soldering part 321 includes a horizontal extension part 321A that extends in the width direction from the lower end of the press-fit part 320 and a curve part 321B that curves upward from the horizontal extension part 321A.

The electrical contact spring piece 322 is a part that functions as an electrical contact point of the CPU board 201 shown in FIG. 2 with the corresponding pad 206. As shown in FIG. 16, the electrical contact spring piece 322 includes a spring piece joining part 325, an easily elastically deformable part 326, and a contact part 327. The spring piece joining part 325, the easily elastically deformable part 326, and the contact part 327 are continuous in this recited order.

The spring piece joining part 325 extends downward from the upper end of the press-fit part 320.

The easily elastically deformable part 326 extends from the lower end of the spring piece joining part 325 and is formed in a U-shape that is convex in the width direction. Specifically, the easily elastically deformable part 326 includes a lower straight part 326A, a curve part 326B, and an upper straight part 326C. The lower straight part 326A, the curve part 326B, and the upper straight part 326C are continuous in this recited order. The lower straight part 326A and the upper straight part 326C are opposed to each other in the vertical direction. The lower straight part 326A and the upper straight part 326C are joined through the curve part 326B.

The contact part 327 is a part that can come into electrical contact with the corresponding pad 206 of the CPU board 201 shown in FIG. 2. The contact part 327 is placed at the end of the upper straight part 326C of the easily elastically deformable part 326, and it is formed to curve to be convex upward.

FIG. 15 shows the state where each contact 300 is attached to each contact accommodation part 284. In order to attach each contact 300 to each contact accommodation part 284, each contact 300 is press-fit into the press-fitting space 301 of each contact accommodation part 284 from the input-output board opposed surface 250B side. At this time, the two press-fit claws 324 of the press-fit part 320 shown in FIG. 16 respectively bite into the two pitch partition surfaces 304. In more detail, each of the two press-fit claws 324 of the press-fit part 320 shown in FIG. 16 bites into the press-fit surface 305A of the press-fit groove 305 formed on the two pitch partition surfaces 304.

When each contact 300 is attached to each contact accommodation part 284, the easily elastically deformable part 326 is accommodated in the press-fitting space 301, and the contact part 327 thereby projects upward from the CPU board opposed surface 250A. The height of projection of the contact part 327 of the electrical contact spring piece 322 from the CPU board opposed surface 250A in the state where the contact part 327 of the electrical contact spring piece 322 is not in contact with the corresponding pad 206 of the CPU board 201 is referred to as a projecting height 327X. Further, the soldering part 321 passes through the notch 308 and reaches the solder connection checking hole 302. In more detail, the horizontal extension part 321A of the soldering part 321 extends in the width direction inside the notch 308, and the curve part 321B is located in the solder connection checking hole 302. In this state, while the press-fit part 320 comes into contact with the separating wall 303 of the housing 250, the soldering part 321 and the electrical contact spring piece 322 do not come into contact with the housing 250.

FIG. 15 shows the state where the soldering part 321 is connected by soldering to the corresponding pad 215 of the input-output board 203. As shown in FIG. 15, when the soldering part 321 is connected by soldering to the pad 215, a solder fillet 330 is formed between the curve part 321B of the soldering part 321 and the pad 215. In general, the soldering part 321 is regarded as being normally soldered to the pad 215 upon formation of the solder fillet 330. Thus, in this embodiment, the housing 250 is provided with the solder connection checking hole 302, so that the presence of the solder fillet 330 is checked from above through the solder connection checking hole 302. This enables determining whether the solder connection of each contact 300 is successfully made or not after surface-mounting the connector 202 onto the input-output board 203.

In this embodiment, the separating wall 303 that separates the press-fitting space 301 from the solder connection checking hole 302 is formed as described above. The presence of the separating wall 303 prevents shavings of the housing 250, which can be generated when press-fitting the press-fit part 320 into the press-fitting space 301, from moving into the solder connection checking hole 302. This allows checking the solder fillet 330 from above through the solder connection checking hole 302 with no problem.

As shown in FIGS. 1 and 2, when the CPU board 201 is pressed against the connector 202 by using the first bolt 211 and the second bolt 212 as described above, the contact part 327 of the electrical contact spring piece 322 of each contact 300 shown in FIG. 15 is elastically displaced downward, and then the plurality of pads 206 of the connector opposed surface 201A of the CPU board 201 shown in FIG. 2 come into plane contact with the CPU board opposed surface 250A of the housing 250 of the connector 202 shown in FIG. 3. At this time, the connector opposed surface 201A of the CPU board 201 is not in contact with the first hold-down 252 and the like.

After that, when the CPU board 201 is further pressed against the connector 202 by using the first bolt 211 and the second bolt 212, the first shield pad 206A or the like of the connector opposed surface 201A of the CPU board 201 comes into contact with the hold-down elastic piece 252P of the first hold-down 252 and the like, and the hold-down elastic piece 252P of the first hold-down 252 and the like are elastically displaced downward. Then, the housing 250 moves downward relative to the first hold-down 252 and the like, with the soldering part 252B shown in FIG. 8 sliding on the first hold-down press-fit groove 270. Eventually, the connector opposed surface 201A of the CPU board 201 is received by the reinforcing plate part 252A of the first hold-down 252 and the like that is soldered to the input-output board 203. This restricts the downward movement of the housing 250 relative to the first hold-down 252 and the like.

The first embodiment is described above, and the above-described first embodiment has the following features.

As shown in FIGS. 1 and 2, the connector 202 (board-to-board connector) is mounted on the input-output board 203 (first board). The connector 202 is interposed between the input-output board 203 and the CPU board 201 (second board), and thereby the plurality of pads 215 of the input-output board 203 and the plurality of pads 206 of the CPU board 201 are respectively electrically connected to one another. The connector 202 includes the flat-plate housing 250, the plurality of contacts 300 held on the housing 250, and the first hold-down 252 and the like (hold-down) made of metal. The housing 250 includes the CPU board opposed surface 250A (second board opposed surface) to be opposed to the CPU board 201. On the CPU board opposed surface 250A, the first hold-down accommodation recess 280 and the like (hold-down accommodation recess) is formed. As shown in FIGS. 7 to 12, the first hold-down 252 includes the soldering part 252B connectable by soldering to the corresponding pad 216 of the input-output board 203, the reinforcing plate part 252A accommodated in the first hold-down accommodation recess 280 and covering the inner bottom surface 280A of the first hold-down accommodation recess 280, and the hold-down elastic piece 252P supported like a cantilever beam by the reinforcing plate part 252A. The hold-down elastic piece 252P includes the elastic piece body 252Q extending from the reinforcing plate part 252A and the curve contact part 252R (contact part) formed at the end of the elastic piece body 252Q and projecting toward the CPU board 201 beyond the CPU board opposed surface 250A. The housing 250 is formed in such a way that the curve contact part 252R does not come into contact with the housing 250 when the curve contact part 252R no longer projects toward the CPU board 201 beyond the CPU board opposed surface 250A as a result of the curve contact part 252R being elastically displaced toward the input-output board 203. In this structure, flexible elastic displacement of the curve contact part 252R is achieved. The same applies to the second hold-down accommodation recess 281 and the like.

Further, as shown in FIG. 10, the contact part recess 280B opposed to the curve contact part 252R in the vertical direction is formed on the inner bottom surface 280A of the first hold-down accommodation recess 280. In this structure, the structure in which the curve contact part 252R does not come into contact with the housing 250 when the curve contact part 252R no longer projects toward the CPU board 201 beyond the CPU board opposed surface 250A as a result of the curve contact part 252R being elastically displaced toward the input-output board 203 is implemented in a simplified way. The same applies to the second hold-down accommodation recess 281 and the like.

Further, as shown in FIGS. 10 to 12, the contact part recess 280B is formed in such a way that the curve contact part 252R does not come into contact with the inner bottom surface 280C of the contact part recess 280B when the curve contact part 252R no longer projects toward the CPU board 201 beyond the CPU board opposed surface 250A as a result of the curve contact part 252R being elastically displaced toward the input-output board 203. In this structure, the structure in which the curve contact part 252R does not come into contact with the housing 250 when the curve contact part 252R no longer projects toward the CPU board 201 beyond the CPU board opposed surface 250A as a result of the curve contact part 252R being elastically displaced toward the input-output board 203 is implemented in a more simplified way. The same applies to the second hold-down accommodation recess 281 and the like.

Note that, instead of the contact part recess 280B, a hole or a notch that is opposed to the curve contact part 252R in the vertical direction and penetrates the housing 250 in the vertical direction may be formed on the inner bottom surface 280A of the first hold-down accommodation recess 280. In this case also, the structure in which the curve contact part 252R does not come into contact with the housing 250 when the curve contact part 252R no longer projects toward the CPU board 201 beyond the CPU board opposed surface 250A as a result of the curve contact part 252R being elastically displaced toward the input-output board 203 is implemented in a simplified way.

Further, as shown in FIG. 10, the elastic piece body 252Q of the hold-down elastic piece 252P extends in parallel to the CPU board opposed surface 250A.

Further, as shown in FIG. 10, the curve contact part 252R is formed in a curve convex toward the CPU board 201. In this structure, high connection reliability between the curve contact part 252R and the corresponding first shield pad 206A and the like of the CPU board 201 is achieved.

Further, as shown in FIG. 15, each contact 300 includes the electrical contact spring piece 322 that projects toward the CPU board 201 from the CPU board opposed surface 250A. The projecting height 327X of the electrical contact spring piece 322 from the CPU board opposed surface 250A in the state where the electrical contact spring piece 322 of each contact 300 is not in contact with the corresponding pad 206 of the CPU board 201 is greater than the projecting height 252X of the hold-down elastic piece 252P from the CPU board opposed surface 250A in the state where the hold-down elastic piece 252P of the first hold-down 252 shown in FIG. 11 is not in contact with the corresponding first shield pad 206A of the CPU board 201. In this structure, the wiping effect between the electrical contact spring piece 322 and the corresponding pad 206 of the CPU board 201 is sufficiently achieved.

Note that the connector 202 includes a plurality of hold-downs including the first hold-down 252 and the like. Alternatively, the connector 202 may include only one hold-down.

First Technical Idea: No. 0170

Further, as shown in FIGS. 1 and 2, the connector 202 (board-to-board connector) is mounted on the input-output board 203 (first board). The connector 202 is interposed between the input-output board 203 and the CPU board 201 (second board), and thereby the plurality of pads 215 of the input-output board 203 and the plurality of pads 206 of the CPU board 201 are respectively electrically connected to one another. As shown in FIG. 6, the connector 202 includes the rectangular flat-plate housing 250 having the first positioning hole 209 and the second positioning hole 210, and the contact row 251A (first contact row) and the contact row 251F (second contact row) held on the housing 250. The housing 250 includes the first pitch side surface 262 (first side surface) and the second pitch side surface 263 (second side surface), which is an opposite side of the first pitch side surface 262. The contact row 251A and the contact row 251F extend from the first pitch side surface 262 to the second pitch side surface 263. The first positioning hole 260 is disposed between the first pitch side surface 262 and the contact row 251A, and the second positioning hole 261 is disposed between the first pitch side surface 262 and the contact row 251F. In this structure, the first positioning hole 260 and the second positioning hole 261 are concentrated on the first pitch side surface 262 side, which contributes to the size reduction of the connector 202.

Further, as shown in FIG. 6, the connector 202 further includes the contact row 251D (third contact row) that is disposed between the contact row 251A and the contact row 251F and extends from the first pitch side surface 262 to the second pitch side surface 263. The distance D1 between the contact row 251A and the first pitch side surface 262, the distance D2 between the contact row 251F and the first pitch side surface 262, and the distance D3 between the contact row 251D and the first pitch side surface 262 satisfy the relationships of D3<D1 and D3<D2. This structure enables an increase in the number of the contacts 300 by utilizing the space between the first positioning hole 260 and the second positioning hole 261.

Further, as shown in FIG. 6, the first nut notch 271 (notch) that is open to the first pitch side surface 262 is formed between the first positioning hole 260 and the second positioning hole 261. This structure allows the first nut notch 271 to be formed by utilizing the space between the first positioning hole 260 and the second positioning hole 261, which contributes to the size reduction of the connector 202.

Further, as shown in FIG. 6, the distance E1 between the contact row 251A and the second pitch side surface 263, the distance E2 between the contact row 251F and the second pitch side surface 263, and the distance E3 between the contact row 251D and the second pitch side surface 263 satisfy the relationships of E3>E1 and E3>E2. This structure allows a space between the contact row 251A and the contact row 251F in the vicinity of the second pitch side surface 263. This space can be used for forming the second nut notch 274, for example.

Further, as shown in FIGS. 7 and 8, the connector 202 further includes the first hold-down 252 (reinforcing member) made of metal. The housing 250 includes the CPU board opposed surface 250A (second board opposed surface) to be opposed to the CPU board 201. The first hold-down 252 includes the reinforcing plate part 252A that covers the CPU board opposed surface 250A around the first positioning hole 260. This structure allows the enlarging deformation of the first positioning hole 260 to be inhibited by the first hold-down 252, which prevents significant degradation of the positioning accuracy by the first positioning hole 260. The same applies to the second hold-down 253.

Further, as shown in FIG. 8, the first hold-down 252 is disposed in such a way that the reinforcing plate part 252A of the first hold-down 252 does not cover the inner edge 260A of the first positioning hole 260 when viewed from above. In this structure, the positioning function exerted by the first positioning hole 260 is not hindered by the first hold-down 252. The same applies to the second hold-down 253.

Further, as shown in FIG. 4, each contact row 251 includes the plurality of contacts 300. As shown in FIG. 12, each contact 300 includes the electrical contact spring piece 322 that projects upward from the CPU board opposed surface 250A. As shown in FIG. 5, the first hold-down accommodation recess 280 (accommodation recess) that accommodates the reinforcing plate part 252A of the first hold-down 252 is formed on the CPU board opposed surface 250A of the housing 250. In this structure, the reinforcing plate part 252A of the first hold-down 252 does not project upward beyond the CPU board opposed surface 250A, and therefore the downward elastic deformation of the electrical contact spring piece 322 is not hindered. The same applies to the second hold-down 253, the third hold-down 254, and the fourth hold-down 255.

Further, as shown in FIG. 8, the first hold-down 252 further includes the soldering part 252B that projects toward the input-output board 203 from the reinforcing plate part 252A of the first hold-down 252 and is connectable by soldering to the pad 215 of the input-output board 203. According to this structure, when the CPU board 201 is pressed against the connector 202 and thereby the housing 250 moves downward relative to the first hold-down 252, the first hold-down 252 receives the CPU board 201 and thereby restricts the further movement of the CPU board 201. The same applies to the second hold-down 253, the third hold-down 254, and the fourth hold-down 255.

Second Technical Idea, No. 0174

As shown in FIGS. 1 and 2, the connector 202 (board-to-board connector) is mounted on the input-output board 203 (first board). The connector 202 is interposed between the input-output board 203 and the CPU board 201 (second board), and thereby the plurality of pads 215 of the input-output board 203 and the plurality of pads 206 of the CPU board 201 are respectively electrically connected to one another. As shown in FIGS. 3 to 5, the connector 202 includes the flat-plate housing 250 made of insulating resin having the first positioning hole 209 and the second positioning hole 210, the plurality of contacts 300 held on the housing 250, and the first hold-down 252 and the second hold-down 253 made of metal disposed to correspond to the first positioning hole 260 and the second positioning hole 261, respectively. The housing 250 includes the CPU board opposed surface 250A (second board opposed surface) to be opposed to the CPU board 201. As shown in FIG. 8, the first hold-down 252 includes the reinforcing plate part 252A that covers the CPU board opposed surface 250A around the first positioning hole 260. Likewise, as shown in FIG. 9, the second hold-down 253 includes the reinforcing plate part 253A that covers the CPU board opposed surface 250A around the second positioning hole 261. This structure allows the enlarging deformation of the first positioning hole 260 to be inhibited by the first hold-down 252, which prevents significant degradation of the positioning accuracy by the first positioning hole 260. The same applies to the second hold-down 253. Further, as shown in FIG. 8, the first hold-down 252 is disposed in such a way that the reinforcing plate part 252A of the first hold-down 252 does not cover the inner edge 260A of the corresponding first positioning hole 260 when viewed from above. In this structure, the positioning function exerted by the first positioning hole 260 is not hindered by the first hold-down 252. The same applies to the second hold-down 253.

Further, as shown in FIG. 12, each contact 300 includes the electrical contact spring piece 322 that projects upward from the CPU board opposed surface 250A. As shown in FIG. 5, the first hold-down accommodation recess 280 (accommodation recess) that accommodates the reinforcing plate part 252A of the first hold-down 252 is formed on the CPU board opposed surface 250A of the housing 250. In this structure, the reinforcing plate part 252A of the first hold-down 252 does not project upward beyond the CPU board opposed surface 250A, and therefore the downward elastic deformation of the electrical contact spring piece 322 is not hindered. The same applies to the second hold-down 253.

Further, as shown in FIG. 8, the first positioning hole 260 is a round hole. The reinforcing plate part 252A of the first hold-down 252 has the penetrating hole 252C (round hole) that is larger than the first positioning hole 260. The first hold-down 252 is disposed in such a way that the inner edge 260A of the first positioning hole 260 is located radially inward with respect to the inner edge 252D of the penetrating hole 252C of the reinforcing plate part 252A of the first hold-down 252 when viewed from above. According to this structure, the structure where the reinforcing plate part 252A of the first hold-down 252 does not cover the inner edge 260A of the corresponding first positioning hole 260 is achieved in a rational way.

Further, as shown in FIG. 9, the second positioning hole 261 has the inner edge 261A including the two straight edge parts 261B that are parallel to each other. The reinforcing plate part 253A of the second hold-down 253 has the penetrating hole 253C (hole) having the inner edge 253D including the two straight edge parts 253E that are parallel to each other. The distance 253F between the two straight edge parts 253E of the reinforcing plate part 253A of the second hold-down 253 is longer than the distance 261C between the two straight edge parts 261B of the second positioning hole 261. The second hold-down 253 is disposed in such a way that the two straight edge parts 261B of the second positioning hole 261 are located between the two straight edge parts 253E of the reinforcing plate part 253A of the second hold-down 253 when viewed from above. According to this structure, the structure where the reinforcing plate part 253A of the second hold-down 253 does not cover the inner edge 261A of the corresponding second positioning hole 261 is achieved in a rational way.

Further, as shown in FIG. 8, the first hold-down 252 further includes the soldering part 252B that projects toward the input-output board 203 from the reinforcing plate part 252A of the first hold-down 252 and is connectable by soldering to the pad 215 of the input-output board 203. According to this structure, when the CPU board 201 is pressed against the connector 202 and thereby the housing 250 moves downward relative to the first hold-down 252, the first hold-down 252 receives the CPU board 201 and thereby restricts the further movement of the CPU board 201. The same applies to the second hold-down 253.

Third Technical Idea, No. 0166

As shown in FIGS. 1 and 2, the connector 202 is mounted on the input-output board 203 (first board). The connector 202 includes the flat-plate housing 250 made of insulating resin and the contact 300 held on the housing 250 by press-fitting. As shown in FIG. 15, the housing 250 includes the press-fitting space 301 and the solder connection checking hole 302. The contact 300 includes the press-fit part 320 to be press-fit into the press-fitting space 301, and the soldering part 321 that extends from the press-fit part 320 and is connected by soldering to the pad 215 of the input-output board 203. The solder connection checking hole 302 is formed to penetrate the housing 250 in the vertical direction and allow the solder fillet 330, which is formed when the soldering part 321 is soldered to the pad 215 of the input-output board 203, to be checked through the solder connection checking hole 302. The housing 250 includes the separating wall 303 that separates the press-fitting space 301 from the solder connection checking hole 302. In this structure, the presence of the separating wall 303 prevents shavings of the housing 250 that can be generated when press-fitting the press-fit part 320 into the press-fitting space 301 from moving into the solder connection checking hole 302. This enables checking the solder fillet 330 from above through the solder connection checking hole 302 with no problem.

Further, as shown in FIG. 15, the press-fit part 320 is configured to bite into the pitch partition surface 304 (surface) that is the inner surface of the press-fitting space 301 and different from the first separating surface 306 (surface) constituting the separating wall 303. In this structure, no load is placed on the separating wall 303 when press-fitting the press-fit part 320 into the press-fitting space 301. This eases restrictions in terms of strength design of the separating wall 303.

Further, as shown in FIG. 15, the curve part 321B of the soldering part 321 is located inside the solder connection checking hole 302. This structure allows the boundary between the solder fillet 330 and the contact 300 to be checked through the solder connection checking hole 302 and thereby achieves more accurate determination as to whether the solder connection in the soldering part 321 is successfully made or not.

Note that, in FIG. 15, the continuity between the contact 300 and the pad 215 may be checked by inserting a probe needle into the solder connection checking hole 302 and making the probe needle come into contact with the curve part 321B of the soldering part 321, and further making another probe needle come into contact with a circuit pattern of the input-output board 203, which is electrically continuous with the pad 215. In this case also, the movement of shavings of the housing 250 that can be generated when press-fitting the press-fit part 320 into the press-fitting space 301 into the solder connection checking hole 302 is inhibited as described above, which allows the probe needle to easily come into contact with the curve part 321B of the soldering part 321.

Second Embodiment

A second embodiment is described hereinafter with reference to FIG. 17. Hereinafter, differences of this embodiment from the above-described first embodiment are mainly described, and redundant description is omitted.

In the above-described first embodiment, the first nut notch 271 for avoiding the physical interference between the first nut 231 and the housing 250 is formed on the housing 250 as shown in FIGS. 1 and 5. Likewise, the second nut notch 274 for avoiding the physical interference between the second nut 232 and the housing 250 is formed on the housing 250.

On the other hand, in this embodiment, as shown in FIG. 17, a first nut penetrating hole 380 for avoiding the physical interference between the first nut 231 and the housing 250 is formed on the housing 250, instead of the above-described first nut notch 271. Likewise, a second nut penetrating hole 381 for avoiding the physical interference between the second nut 232 and the housing 250 is formed on the housing 250, instead of the above-described second nut notch 274.

Further, in the above-described first embodiment, as shown in FIG. 4, the connector 202 includes the first hold-down 252, the second hold-down 253, the third hold-down 254, and the fourth hold-down 255. The first hold-down 252, the second hold-down 253, the third hold-down 254, and the fourth hold-down 255 are separate parts.

On the other hand, in this embodiment, as shown in FIG. 17, the first hold-down 252, the second hold-down 253, the third hold-down 254, and the fourth hold-down 255 are formed integrally so that they are continuous with one another. In this manner, by forming the first hold-down 252, the second hold-down 253, the third hold-down 254, and the fourth hold-down 255 as one part, high electromagnetic shield effect is obtained.

To be specific, the connector 202 includes an entire hold-down 382 (hold-down). The entire hold-down 382 includes the first hold-down 252, the second hold-down 253, the third hold-down 254, and the fourth hold-down 255. The entire hold-down 382 is formed annularly so as to surround the plurality of contacts 300 when viewed from above. The entire hold-down 382 includes a reinforcing plate part 383, a plurality of soldering parts 384, and a plurality of hold-down elastic pieces 400.

A first entire hold-down accommodation recess 401 (hold-down accommodation recess) and a second entire hold-down accommodation recess 402 (hold-down accommodation recess) are formed on the CPU board opposed surface 250A of the housing 250.

The first entire hold-down accommodation recess 401 is formed in a U-shape to surround the first nut penetrating hole 380 when viewed from above. An inner bottom surface 401A of the first entire hold-down accommodation recess 401 has two contact part recesses 401B. Each of the contact part recesses 401B has an inner bottom surface 401C.

The second entire hold-down accommodation recess 402 is formed in a U-shape to surround the second nut penetrating hole 381 when viewed from above. An inner bottom surface 402A of the second entire hold-down accommodation recess 402 has two contact part recesses 402B. Each of the contact part recesses 402B has an inner bottom surface 402C.

The reinforcing plate part 383 is a part that covers the inner bottom surface 401A of the first entire hold-down accommodation recess 401 and the inner bottom surface 402A of the second entire hold-down accommodation recess 402. The reinforcing plate part 383 includes the reinforcing plate part 252A of the first hold-down 252, the reinforcing plate part 253A of the second hold-down 253, the reinforcing plate part 254A of the third hold-down 254, and the reinforcing plate part 255A of the fourth hold-down 255.

The plurality of soldering parts 384 are connectable by soldering to the corresponding pads of the input-output board 203. The plurality of soldering parts 384 include a first soldering part 385, a second soldering part 386, a third soldering part 387, and a fourth soldering part 388.

The first soldering part 385 corresponds to the first pitch side surface 262 of the housing 250.

The second soldering part 386 corresponds to the second pitch side surface 263 of the housing 250.

The third soldering part 387 corresponds to the first width side surface 264 of the housing 250.

The fourth soldering part 388 corresponds to the second width side surface 265 of the housing 250.

The plurality of hold-down elastic pieces 400 include four hold-down elastic pieces 400. The four hold-down elastic pieces 400 are disposed opposite to the inner bottom surfaces 401C of the two contact part recesses 401B and the inner bottom surfaces 402C of the two contact part recesses 402B, respectively, in the vertical direction. Each hold-down elastic piece 400 extends in the pitch direction. The hold-down elastic piece 400 disposed in the first hold-down 252 and the hold-down elastic piece 400 disposed in the third hold-down 254 extend to become closer to each other. The hold-down elastic piece 400 disposed in the second hold-down 253 and the hold-down elastic piece 400 disposed in the fourth hold-down 255 extend to become closer to each other.

The other structure of each hold-down elastic piece 400 and the technical relationship between each hold-down elastic piece 400 and each contact part recess 401B or each contact part recess 402B are the same as those described above and therefore description thereof is omitted.

Note that the first soldering part 385 may have a plurality of slits that divide the first soldering part 385 in the width direction. Likewise, the second soldering part 386 may have a plurality of slits that divide the second soldering part 386 in the width direction. Likewise, the third soldering part 387 may have a plurality of slits that divide the third soldering part 387 in the width direction. Likewise, the fourth soldering part 388 may have a plurality of slits that divide the fourth soldering part 388 in the width direction. Forming a plurality of slits that divide each of the soldering parts 384 in the longitudinal direction of each soldering part 384 as described above enables the absorption of the warpage of the input-output board 203, for example, and contributes to weight reduction of the connector 202.

The above-described embodiments can be combined as desirable by one of ordinary skill in the art.

From the disclosure thus described, it will be obvious that the embodiments of the disclosure may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims. 

What is claimed is:
 1. A board-to-board connector to be mounted on a first board and interposed between the first board and a second board to electrically connect a plurality of pads of the first board with a plurality of pads of the second board respectively, comprising: a flat-plate housing; a plurality of contacts held on the housing; and a hold-down made of metal, wherein the housing includes a second board opposed surface to be opposed to the second board, and a hold-down accommodation recess is formed on the second board opposed surface, the hold-down includes: a soldering part connectable by soldering to a corresponding pad of the first board; a reinforcing plate part accommodated in the hold-down accommodation recess and covering an inner bottom surface of the hold-down accommodation recess; and a hold-down elastic piece supported like a cantilever beam by the reinforcing plate part, the hold-down elastic piece includes an elastic piece body extending from the reinforcing plate part, and a contact part formed at an end of the elastic piece body and projecting toward the second board beyond the second board opposed surface, and the housing is formed in such a way that the contact part does not come into contact with the housing when the contact part no longer projects toward the second board beyond the second board opposed surface as a result of the contact part being elastically displaced toward the first board.
 2. The board-to-board connector according to claim 1, wherein a contact part recess opposed to the contact part in a thickness direction of the housing is formed on the inner bottom surface of the hold-down accommodation recess.
 3. The board-to-board connector according to claim 2, wherein the contact part recess is formed in such a way that the contact part does not come into contact with an inner bottom surface of the contact part recess when the contact part no longer projects toward the second board beyond the second board opposed surface as a result of the contact part being elastically displaced toward the first board.
 4. The board-to-board connector according to claim 1, wherein a hole or a notch opposed to the contact part in a thickness direction of the housing and penetrating the housing in the thickness direction of the housing is formed on the inner bottom surface of the hold-down accommodation recess.
 5. The board-to-board connector according to claim 1, wherein the elastic piece body of the hold-down elastic piece extends in parallel to the second board opposed surface.
 6. The board-to-board connector according to claim 1, wherein the contact part is formed in a curve convex toward the second board.
 7. The board-to-board connector according to claim 1, wherein each of the contacts includes an electrical contact spring piece projecting toward the second board from the second board opposed surface, and a projecting height of the electrical contact spring piece of each contact from the second board opposed surface in a state where the electrical contact spring piece is not in contact with a corresponding pad of the second board is greater than a projecting height of the hold-down elastic piece of the hold-down from the second board opposed surface in a state where the hold-down elastic piece is not in contact with a corresponding pad of the second board.
 8. The board-to-board connector according to claim 1, wherein the hold-down is formed annularly so as to surround the contacts when viewed in a thickness direction of the housing.
 9. The board-to-board connector according to claim 8, wherein the hold-down includes a plurality of the hold-down elastic pieces.
 10. The board-to-board connector according to claim 1, wherein the hold-down made of metal is a single discrete component.
 11. The board-to-board connector according to claim 1, further comprising a second hold-down, a third hold-down, and a fourth hold-down. 